An organic electroluminescent device (organic EL device) is a promising solid-state emitting type inexpensive and large full-color display device, and has been extensively developed. In general, an organic EL device includes an emitting layer and a pair of opposing electrodes holding the emitting layer therebetween. When an electric field is applied between the electrodes, electrons are injected from the cathode and holes are injected from the anode. The electrons recombine with the holes in the emitting layer to produce an excited state, and energy is emitted as light when the excited state returns to the ground state.
Early organic EL devices are insufficient in driving voltage, luminous efficiency and durability, and various technical improvements have been made for the problems.
The improvements of luminous efficiency and lifetime of the organic EL device are important subjects which lead to a low power consumption of display and improvement of durability. Therefore, further improvement is required.
To solve the problems, Patent Document 1 discloses a triarylamine derivative which can be used as a hole-transporting material and emitting material. This triarylamine derivative has an electron-trapping function. Patent Document 2 discloses a compound having a specific structure in which a diarylamine or nitrogen-containing heterocyclic group bonds via a biphenylene linking group.
Patent Document 3 tries to improve device performance using a compound with a heterocyclic group (pyrimidine, triazine and the like) containing at least two nitrogen atoms at certain positions. Patent Document 4 discloses a compound having a pyrimidine skeleton for an electrophotographic photoreceptor.
[Patent Document 1]JP-A-H11-222590[Patent Document 2]JP-A-2005-085658[Patent Document 3]JP-A-2009-246097[Patent Document 4]JP-A-H02-052360